Heterogeneity analysis of the human pituitary proteome

A human proteome is relatively dynamic compared with its corresponding genome. Our aim was to study the heterogeneity of a human pituitary proteome as a function of gender, age, and race.

Pituitary control tissues (n = 8) were used to extract proteins; each control tissue was analyzed (n = 3-5) with two-dimensional gel electrophoresis (2DGE) and PDQuest software. We obtained 30 high-resolution 2DGE gels and conducted a comparative analysis as a function of gender, age, and race. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry and liquid chromatography-electrospray ionization-quadrupole-ion trap tandem mass spectrometry were used to characterize the protein in each differential spot.

We detected approximately 1000 protein spots in each 2DGE map, and 51 differential spots (7 differing with gender, 17 with age, 15 with race, and 12 with the coeffect of age and race). Among those 51, we characterized 28 proteins [5 differing with gender, 8 with age, 6 with race, 8 with the coeffect of age and race, and 1 (somatotropin chain 1) with all of these]. Somatotropin was related to gender, age, and race, and prolactin was higher in females than males. The differentially expressed proteins that were related to age were mainly those proteins associated with cell growth, proliferation, differentiation, apoptosis, and death; those proteins showed no difference with gender and race. Age and race affected some proteins associated with hormone regulation (e.g., follistatin, thyroid hormone receptor beta-2, adenylate cyclase-inhibiting Galpha protein).

A heterogeneity exists in the human pituitary proteome as a function of gender, age, and race. These findings will serve as a basis for our comparative proteomics studies of human pituitary adenomas.